The historic Twining Court Stables property near Dupont Circle is being developed into an enclave of 15 upper-priced town houses by Angelo Puglisi. The three-story, traditional dwellings will face a landscaped courtyard controlled by a security gate on the north side of O Street NW, between 21st and 22d streets. Burr, Morris & Pardoe, which is handling sales, said that late summer deliveries are planned.

The National Land Liquidation Bureau Inc., 1028 Connecticut Ave. NW, will have its first Washington area auction of varied country-style land sites on May 12 at 9:30 a.m. at the International Inn. More than 70 properties will be offered.

Heritage Realty, which has offices in Annapolis, Crofton, Bowie and Dunkirk, has been purchased by James Denny and Fred Pritt. Denny has assumed the presidency of the firm that has 90 sales agents. James Cunningham is now executive vice president and general manager. James Waggoner, the former owner, remains with the firm as a district vice president. The firms plans to open four new offices before the end of this year.

H.G. Smithy Co. has announced the placement of $9 million in mortgage financing on the Barracks Road Shopping Center in Charlottesville, va. Owned by the Virginia Real Estate Investment Trusts, the shopping center has 480,000 square feet of space.

An activity center and health club was opened recently at Sea Colony, the year-around beach resort and tennis community being completed by Carl M. Freeman & Associates on an ocean-front site in South Bethany, Del. The high-rise community has 800 condominium apartments and some nearby town houses.

A HUD program to encourage home ownership by women is part of the training conference of the Women's Equality Action League under way this weekend at the £4Enfant Plaza Hotel in Southeast.

Leggatt, McCall & Werner Co. Inc. has relocated its Washington office to 1919 Pennsylvania Ave. NW., a new office building by Quadrangle Corp. The LMW firm specializes in commercial and industrial real estate brokerage.

The Neighborhood Housing Service will hold a series of energy conservation workshops beginning May 19 at 10 a.m. in the Professional Building at 2041 Martin Luther King Ave. SE. For information, dial 889-7932.

Construction has been completed on a large addition to the three-story Flow General building at Tysons Corner. The building is owned by the Donatelli & Klein investing firm of Bethesda. Flow General, a research firm, now has 233,557 square feet of space on the expanded site in the Westage-Westpark Industrial Park.

Enterprise Developers, a subsidiary of MCD Holdings Inc., now is building large homes priced from $136,100 on 2-to-4-acre sites in Lake of the Pines near Annapolis. Fifty-eight estate homes are planned in the 182-acre site on Rossback Road near Rte. 50.

Thirteen model homes by three different builders will be opened next month in the new Huntington neighborhood of the Village of Kings Contrivance in Columbia, Md. The neighborhood will have a mixture of single houses, town houses and garden apartments. The builders in the new section are Columbia Builders Inc., Ryland Homes and the Fred Pritt Building co.